With the development of wireless communication technologies, increasing numbers of mobile phones and PDAs now include digital cameras as a special feature.
Generally, digital cameras are image recording media capable of photographing a plurality of still images without using film. Such a digital camera typically uses an image pickup device, which is a kind of semiconductor device, such as a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS). In the digital camera, an object image formed on the image pickup device through a lens is converted into an electronic signal by the image pickup device, and the electrical signal is stored as a digital signal, for example, either in the camera unit or in a mobile phone or PDA in which the digital camera is mounted.
Since the digital camera is to be mounted in a small mobile phone or PDA, a fixed focus lens module is usually used to facilitate mounting thereof. However, images photographed by a digital camera module with a fixed focus lens module tend to be of poor quality. This is partly due to the fixed focus lens, which is incapable of adjusting distance between the lens and the image pickup device to make a clearer image when photographing objects at different distances from the camera.
A typical focusing structure has a focusing adjusting apparatus using a thread structure, which includes a lens module and a base. The base includes an image sensor. When adjusting focus, the lens module needs to be extensible or compressible relative to the base so that the distance between the lens module and the image sensor is changed. Therefore, a space above/over the lens module is required in order to provide the movement space. Furthermore, the lens module will rotate relative to the base at work. This structure causes eccentricity problems so as to effect the image quality.
Therefore, a digital camera with a focusing function is desired in order to overcome the above-described shortcomings.